People talking on cell phones while driving are at least four times more likely to be involved in a collision and using a hands-free device does virtually nothing to reduce the risk, research shows.

The University of Sydney study, based on a survey of 400 car crash victims, found that people using hand-held phones were five times more likely to have a collision.

It also found that people using hands-free devices while driving were four times more likely to have a crash resulting in injuries.

Governments around the world, including Germany, Australia and several U.S. states, have prohibited the use of hand-held cell phones while driving, but the new research, published in the British Medical Journal, suggests the ban should be widened.

“This research has highlighted that hands-free isn’t fine, that it does also elevate your risk of crashing,” study co-author Professor Mark Stevenson told Reuters on Thursday.

“The key message here is that we need to basically avoid using phones whilst driving. That is what is going to minimise your risk,” said Stevenson, of The George Institute’s Injury Prevention and Trauma Care Division at Sydney University.

The research included talking on phones and sending text messages while driving, he said.

The study involved more than 400 drivers and was conducted in the emergency departments of three hospitals in Western Australia state.

Dr Suzanne McEvoy, the report’s principal author, said more than half of the study participants reported having a hands-free phone device in their vehicles.

“The increased likelihood of crashing was not influenced by gender, age of the driver or availability of a hands-free device,” McEvoy said.

Stevenson said respondents agreed to have their billing records made available by their phone service providers.

Using those records, researchers compared phone use just before the collision with journeys taken by the same drivers in the week before their crash.

“This is the first study that’s looked at outcomes that are injury-related,” Stevenson said.

He said researchers looked at whether drivers had been using their phones up to 10 minutes before their collision. “The majority were in a very short time period just before the crash.”